Currently, inkjet printers and copiers work by a cartridge or inkjet printhead ejecting a small amount of ink onto a desired location on a piece of paper. The ink droplet of micron dimensions first impacts the paper and then wets or spreads on the surface of the paper because of surface tension. Oftentimes, due to the strong absorbency and roughness of paper, the ink may spread excessively and unevenly, causing the shape of the droplet as seen from above to diverge undesirably from a compact, well-formed circle (see FIG. 1B). The ink dot upon drying may be noncircular and rough, and the overall printed image grainy instead of sharp.
A number of things can be done to reduce the amount of spreading. The paper can be coated with a thin film, for example, on which the ink droplet spreads poorly. This type of paper, usually sold as "glossy" paper, produces excellent laser-quality print but is also very expensive when compared against "plain" copier or bond paper. Another solution involves changing the properties of the ink, such as increasing its viscosity to reduce spread or choosing its solvent to hasten drying and thereby freeze the droplet before it can spread. However, in many cases, ink with such properties tends to clog the cartridges and mechanisms, thereby decreasing the life of ink cartridge.